Process of preparing dulcitol and mannitol monoborate monocondensation products



Patented 3,

PROCESS I OF PREPARING liULCITOL AND MANNITOL MONOBORATE' MONOCQN- DENSATION PRODUC Clarence Bremer, Tamaqua, Pa., assignor to Atlas Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application March 17, 1938,

Serial No. 196,414

15 Claim.

This invention relates to a process 01' preparing dulcitol and mannitol m'onoborate monocondensation products and alkali metal (including ammonium) salts thereof. g

The principal object of the invention is the production or dulcitol or'mannitol monoborate monocondensation products and alkali metal salts thereof in a. facile and economical manner.

A further object of the invention is the proin duction of the foregoing monocondensation prod- .ucts from dulcitol and mannitol' monoborate and diborate polycondensation products.

A still further object of the invention is the production of dulcitol or mannitol monoborate 15 condensation products and. alkali metal salts thereof, bya process which involves as an intermediate step the preparation of dulcitol or mannitol borate polycondensation products.

Another object of the invention is the produc- 20 tion of non-hydrolyzing aqueous solutions of dulcitol or mamiitol monoborate monocondensa tion products by the hydrolysis of dulcitol or 40 and alkali metal salts thereof. In this application, I claim the method of preparing dulcltol and mannitol monoborate monocondensation products.

The products of the invention are suitable for use in coating compositions for paper and textiles; ingredients in cosmetics and hair waving compounds; ingredients in electrolytic condensers; ingredients in pharmaceutical preparations and adhesives, and for many other uses so where adhesiveness, relatively high viscosity. good one secondary alcohol electrical conductivity, and resistance to hydrolysis are desirable.

In the preparation of dulcitol and ma'nnitol monoborate monocondensation products and alkali metal salts thereof, in which the hydrogen 5 atom of one secondary alcohol group of the hexahydric alcohol has been replaced with the boron radical -B(OH)R, where R is OH or 0M, M being an alkali metal, the condensation of'the hexahydric alcohol and the boron radical to term directly the stable monocondensation product. is

I accomplished with greatest difliculty. Attempts to form a monocondensation product by heating the ingredients to drive ofl only one mol of water result either in failure to obtains. good yield of the desired monocondensation product. or in the'production of a mixture of polycondensation products and unreacted ingredients.

Now I have discovered that when the dulcitol or mannitol borate polycondensation products and alkali metal salts thereoi, as set forth below and in my co-pen'ding application referred to above, are hydrolyzed, the monob'orate monocondensatlon products are produced. Thus, in the production of the monocondensation products in accordance with the present invention, the reaction of the ingredients is carried into the polycondensation stage and the polycondensation product hydrolyzed back to the monocondensation product, or if the polycondensation products are available, they may be hydrolyzed to form the monocondensation products. Where an aqueous medium is employed to effect hydrolysis, solutions oi the stable monocondensation products may be obtained over a wide range of concentration and viscosity. Where the non-alkalized (acidic) monoborate monocondensation product is present in such solutions in sufficient proportion, it may be readily crystallized therefrom. The precipitated crystalline product may beremoved from the solution in any desired manner, as by filtration, decantation, etc.

According to the preferred practice of the in vention, there is prepared initially a water soluble derivative of a hexahydric alcohol selected I5 irom the group consisting oi' :-mannitol and dulcltol-in which-the hydrogen atom of at least group'has been replaced with a boron radical selected i'rom thatgroup oi radicals represented by BRR'; -Blt'R=, so

I where R is OH or 'OM, M being an alkali metal,

R is a bond to the oxygen atom and replaces the hydrogen atom of another secondaryalcohol group oi the hexahydric alcohol, and R is a bond to the oxygen atom and replacesthe hydrogen atom of a thirdalcohol group of the hexahydric alcohol, the boron atom in said boron radical being bonded to the oxygen atom of at least two secondary alcohol groups of the hexahydric alcohol. This derivative is then hydrolyzed by an aqueous medium to form a'stable water soluble derivative of the hexah'ydric alcohol in which the hydrogen atom of one secondary alcohol group has been replaced with the boron radical -B(OH)R, where R is OH or OM, M

' being an alkali metal.

where a is on or OM, M being an alkali metal.

Another example is mannitol 'diborat tetracondensation product of the followingiormu'la:

\1 a BB where R is 01-1 or OM, M being an alkali metal.

densation has taken Another example is dulcitol diborate tetracondensation product which, assuming transconplace, has the following formula':

where R is OH or OM, M being an alkali metal.

Other examples are dulcitol monoborate di condensation product having the empirical formula CcHmOs BR, where R is OH or OM, M being an alkali metal, and dulcitol or mannitol monoborate trlcondensatiorl products having the empirical formula CeHuOe B, the boron atom of the foregoing products being bonded to the oxygen atom 0! at least two secondary alcohol groups oi the hexahydric alcohol.

In this 'speciflcationfwhere pH of a product is referred to, unless otherwise designated,- I mean the pH of a 25% aqueous solution prepared by dissolving 25 parts by weight of the product in '15 parts by weight of water.

The polycondensation products employed inbe either alkallzed or non-althe process may kalized. The non-alkalized polycondensation products are acidic in character and have a pH of about 2.0. The acidic products can be neutralized or made basic in character as desired by the addition thereto of alkalies, such as am- I monium hydroxide, ammonia, sodium hydroxide,

potassium hydroxide, lithium hydroxide, etc.;v or

therequired amount of an alkali metal borate can he substituted for boric acid in the reaction mixture, thereby leading directly to the production of materials of the desired pH. The addition of about 0.75 to 0.80 mol ofaikali per atom of boron in the hexltol borate willproduce a product of pH '7 comprising a mixture of 'alkalized and nonalkalized borates, whereas the addition of one mol of alkali per atom of boron in the hexitoi borate will produce a product consisting of, the corresponding alkali salt having a pH value of about 10.6. For example, a neutral nionoborate dicondensation product (pH of 7.0) may be prepared by reacting one mol of mannitol and .one mol of boric acid and adding to the resinous melt 0.8 mol of sodium hydroxide, per mol of mannitol. However, -if one mol of sodium hydroxide is added to the resinous melt, the pH will be 10.6, which is the pH value of sodium mannitol monoborate dicondensation product. 'A neutral diborate tetraoondensation product of pH '7 may be prepared by reacting one mol of mannitol and two mols of boric acid and adding to the resinous melt 1.5 mols oi sodiumhydroxide which is equivalent to 0.75 mol of sodium hydroxide per atom of boron. Furthermore, if two mols of sodium hydroxide are added to this'resinous melt, the

- pH will be 10.6.

Clear, resin-like polycondensation products employed in the process maybe obtained by'reacting one mol of dulcitol or mannitol with from one to two mols of boric acid. The reaction of mol for mol ratios results in the production or dulcitol or mannitol monoborate dicondensation products when two mols of water have beensplit off, whereas the reaction of one mol of the hexahydric alcohol with two-mols of boric acid results in the formation of dulcitol or mannitol diborate tetracondensation products when four mols of water have been split off.

In the preparation of the polycondensation products, the ingredients are preferably dissolved in a relatively large amount of water, say from 4 to 12 mols of water per mol of dulcitol or man- I :nitol present in the reaction mixture. The use p of such an amount of water is advantageous since it serves as a vehicle and facilitates mixing and reaction of the ingredients. The mixture thus obtained is then heated, preferably at a temperature of to C., for a sufilcient period of time to drive off the water which must be removed to form the desired polycondensation Thus, with a vmixture of one mol of product. mannitol, one mol of boric acid and lomols of water, removal from the reaction mixture of about 12 mols of water results in the production of mannitol monoborate dicondensation product. While the use of an excess of water i referred to above, it is to be understood that where the mixed'melting point oi the ingredients is below the charrlng point, the water of solution rate polycondensation value above 2.0, I find it preferable to react the.

in amount or eliminated comhexahydric alcohol and the boric acid first, and

* alkali metal hydroxide required to adjust the charred or discolored,

to add at the end of the reaction the amount of melt to the desired pH. when the alkali metal is present from the beginning of the reaction, the reaction must be carefully controlled as there is a tendency for the reaction'product to become whereas when it is added after the reaction between the hexahydric alcohol and the boric acid, especially if the-hexahydric alcohol borate melt is permitted to cool to about 100 C. before addition of the alkali metal minimized hydroxide, this difficulty is ;monocondensation It is to be understood, however, that the alkali metal hydroxide may be employed as astarting material in the reaction mixture used to produce the polycondensation products employed in the present invention, or the alkali metal salts of boric acids, such as ammonium borate, sodium metaborate, sodium tetraborate, sodium-perborate, potassium metaborate, potassium tetraborate, lithium metaborate, lithium tetraborate, and the like, may be employed in place of all or part of the boric acid desired, the ingredients may be reacted in amounts which will result in a. product of a pH value above that desired so that subsequent adjustment of pH value can be made downwardly with boric acid. a

The invention is not to be considered as limited with respect to the pH value of the polycondensation products, nor with respect to the manner of obtaining the desired pH value in said products. f

In accordance with the present invention, the foregoing di-, tri-, and tetracondensation products of dulcitol or mannitol, or mixtures thereof, are hydrolyzed to the corresponding monoborate product by dissolving the polycondensation products or mixtures thereof in water. In order to induce this hydrolysis, the

concentration of the solutionis preferably such that the amount of water present is considerably in excess of that theoretically required to convert the di-, trior tetra-condensation product to the monoborate monccondensation product.

Th hydrolysis involves the addition of sufllc'ient water to the polycondensation product to form the corresponding monoborate monocondensation product. monoborate monocondensation products are of the empirical formula-CeHnOaBmmR, where R is OH or QM, M being an alkali metal, in which the boron radical replaces the hydrogen atom of a secondary alcohol group of the hexitol. e

Thus, the reaction involved in the process of forming mannitol monoborate monocondensation product from mannitol monoborate. dicondensation product is as follows:

where R is OK or OM, being an alkali metal.

- condensation product to originally employed.- If

The dulcitol and mannitol In the of mannitoldiborate tetraconde sation product, the reaction is as follows:

where R is OH or OM, M being an alkali metal. It is to= be understood that hydrolysis of the 15 monoborate dicondensation and diborate tetracondensation products of dulcitol similarly involves the addition of l and 3 molecules of water respectively per molecule of the polycondensation products to form dulcitol monoborate monocono densation product.

The hydrolysis of the dulcitol and mannitol tricondensation products involves the addition of 2 molecules of water per molecule of the triform monocondensation product in the following reaction:

Either the non-alkalized or the alkalized poly- 0 condensation products, or mixtures thereof, may be used in carryingout the invention with the production of corresponding monoborate mon0-. condensation products. Where the diborate tetracondensation product is employed, the product of the hydrolysis is a mixture ofthe non-alkalized or alkalized monoborate monocondensation product and orthoboric acid or the alkalized salt thereof, depending upon whether, the tetracondensation product was non-alka- 40 lized or alkalized 4 If it is desired to, obtain the'non-alkalized accordance with monoborate monocondensation product in-crys-' talline form, this may be readily accomplished by hydrolyzing one of the non-alkalized poly- 45 condensation products referred to above to form an aqueous solution of the. non-alkalized'monoborate monocondensation product, and thereafter cooling the solution to 0 C. to cause precipitation of the crystalline non-alkalized mono- 50 borate monocondensation product.

Generally, the crystalline non-alkaiized monocondensation products may also be obtained by cooling aqueous solutions of a mixture of the alkalized and non-alkalized monoborate mono- 55 condensation products obtained in any manner (such as by the hydrolysis and dissolution of a polycondensation product of pH 7) provided that the solution is of a pH below about 10. Precipitation of the non-alkalized monoconden- 6d sation products from solutions of a mixture of the. alkalized and non-alkalized products'becomes more dimcult as the pH of the solution increases from 2 to 10, probably because of the decreased concentration of the non-alkalized monocondensation product in solutions of high pH.

e While, in accordance with the preferred meththe corresponding 25 stroy the hydrolysis advantage.

and from other considerations,

temperatures of dissolution'and separation.

" While water is generally employed to efiect dissolution of the polycondensation products and hydrolysis thereof in accordance with the principles of this invention, the water may be in the form of any aqueous medium which does not prevent the hydrolysis and which does not deproduct. For example, I have found that 95% acetic acid may be used to Below I have given several non-limitlng..ex-' amples of the process of the invention. While these examples set forth specific temperature limits and modes of procedure in making both the polycondensation products and the hydrolytic products, it will be apparent that numerous variations are possible.' Thus, in the preparation or the polycondensation products, higher temperatures may the time is reduced, or lower temperatures may be used if the time is lengthened. The invention contemplates the conversion of the aforesaid hexahydric alcohol borate polycondensation product to the monocondensation product by hydrolysis as outlined above, regardless of the physical form of the polycondensation product. In certain cases, due'to differences in apparatus, it may be found desirable to depart from the exact conditions set forth in the examples. These and other variations, which will be readily apparent to those skilled in the art, may be made without departing from the spirit of my invention, which is to be construed as limited only by the claims appended hereto.

In the examples, the materials prepared by the reaction'of 1 mol of the hexitol and 1 mol of boric acid are designated as monoborates, and those prepared by the reaction of 1 mol of the hexitol and 2 mols of boric acid are designated as diborates. When the materialwas neutrallzed or partially neutralized, there is specified the cation used and the pH to which it was adjusted. The, polyoondensation products are further designated by the terms di-, trior tetracondensation products, depending upon whether 2, 3 or 4 mols of water were lost during the reaction by which they were produced.

Example 1 There was first prepared mannitol monoborate-acidic-dicondensation product; as follows: 182 g. (1 mol) of mannitol and 62 g. (1 mol) of boric acid were dissolved in 180 g. (10 mols) of water. This mixture was heated with agitation at 115-120 C. until the water of solution and 2 mols of water of condensation were given off and the refractive index was about 1.5. The product had a pH of about 2.0 and was a clear, water-white resinous melt.

10 grams of the resinous material thus prepared were dissolved in an equal weight of water by heating a mixture of the resinous material and the water to -80 C. Upon cooling the solution, mannitol monoborate monocondensation separated out in small, needle-like crystals.

' To insure the greatest degree oiprecipitatlon,

the solution was finally cooled -to 0 C. 10 grams of crystalline mannitol monoborate mononcondensation product was obtained, by separation fromthe mother liquor. The product had a melting point of ill-80 C., an empirical formula of Cal-1150a B and a structural formula as given be employed provided above. It was stable and could be repeatedly re-crystallized from water.

Example 2 2.0 mols of water of condensation had volatilized; The product had a pH of about'2.0 and was a clear resinous melt which crystallized in 24 hours to crystals having a melting point of 25 grams of the dulcitol-.monoborate dicondensation productlprepared as above were dissolved in 25 grams of water by heating a mixture of the dicondensatlon product and the water to a temperature of -80 C. Upon cooling the solution, dulcitol monoborate monocondensation product separated out in needle-like crystals. To insure complete precipitation, the solution was cooled to 0 C. The crystals were separated from the mother liquor. The yield was 25 grams of crystalline dulcitol monoborate monocondensation product, having a melting point of 104-108 C. The product had 5 free hydroxyl groups, as determined by the acetin number, while tritylation showed the two primary alcohol groups to be open. Combustion analysis showed it to have an empirical formula of CaHiaOa B. It is a stable compound and can be re-crystallized from water repeatedly.

Example 3 lviannitol diborate acidic tetracondensation product was prepared as follows: 182 g. (1 mol) of mannitol and 124 g. (2 mols) of boric acid were dissolved in 200 g. of water, and the mixture was heated with agitation at 115-120 C. for one hour when it had a refractive index of about 1.48. At the end of this time, not only the water of solution, but also 4.0 mols of water of condensation had been driven oil. The prodnot was a clear water-white resinous melt and had a pH of about 2.1.

25 parts by weight of the tetracondensation product thus prepared were dissolved in 75 parts by weight of water at C. The solution was cooled to 10 C. whereupon-free boric acid crystallized out. The solution was filtered to remove this boric acid' and was cooled to 0 C. whereupon mannitol monoborate rnonocondensation product, having a melting point of 79-80 C.,'orystallized out.

Example 4 of'dulcitol and 124 g. (2 mols) of boric acid were dissolved in 270 g. (15 mols)' or water and the mixture was heated with agitation at -120 C.

for one hour, when the product had a refractive index of about 1.48. At the end of this time the water of solution as well as 4.0 mols of water of condensation had volatilized. A clear resin was obtained which solidified on standing-'24 hours. The solidified material had a melting point of 275-280 C. Analysis showed the prod- I uct to have two free hydroxyls, both oi which were primary, and to have an empirical formula of CeHrzOaBz.

perature tree boric acid was occurred.-

25 parts by weight of the dulcitol diborate tetracondensation product thus produced were dissolved in 75 parts by weight of water at 80 C. The solution was cooled to 10C. at which temobtained. Upon further cooling to 0 C., dulcitol monoborate monoc'ondensation product, having a melting point of 104-108 C., crystallized out.

. Example 5,

36.4 g. (.2 mol) mannitol and 30.8 g. (.2 mol) sodium perborate (NaBOa-4Ih0) were mixed with 36.4 g. of oxygen was evolved very rapidly. As soon as this reaction had ceased, the mixture was heated with agitation at.110-115 C. until all water of solution and crystallization as well as 7.2 grams of water'of condensation had been volatilized. A clear resin-like melt, which was of a light brown color, was obtained. The product had a pH of 8.8 and about four free hydroxyls as determined by acetin number.

The product prepared as above was dissolvedin water whereupon hydrolysis took place, iorming a mixture of alkalized and non-alkalized mannitol monoborate monocondensation product. Upon cooling25-50% aqueous solutions of the product to 0 alkalized monobo ate monocondensation product Example 6 The polycondensation product employed in this example was prepared as follows: 182 g. (1 mol) of mannitol and 62 g. (1 mol) of boric acid were dissolved in 180 g. (10 mols) of water. The mixture was heated with agitation at 115- 120 C. for approximately one hour until the refractive index was about 1.51. At this of the water of solution and approxlmately 2A mols of water of condensation had volatilized. The product, had a pH of about.2.0 and was a clear water-white resinous melt. Analysis showed it to contain of the dioondensation product having the structural tormula given. above and an empirical formula of C(iHiaOlB and 40% of the tricondensation product having the empirical formula CcHnOsB. Tritylation showed two primary alcohol groups to be open. It had a melting point r 160-167" 0.

. Two grams of this productwere dissolved by heating in 25 ml. of glacial aceticacldto which had been added 1.2 ml. of distilled water. Upon cooling the solution 1.7 g. 01' crystalline mannitol monoborate monocondensation product having a melting'point or IQ-80 C. were obtained.

Example 7 10 grams of the mixture 0! d1 and tri-conin Example 0 were densation products utilized A dissolved in 10 grams of water by heating to 80 C. Upon cooling to0 C., 10 g. of crystals of mannitol monoborate monocondensation product having a melting point of 70-80 C. were obtained. This was separated from the mother liquor by filtration.

Example 8 Mannitol monoborate dicondensation product was prepared as follows: 45.5 gms. (0.25 mol) of mannitol and 15.5 gms. (0.25 mol) oiHaBOa were thoroughly mixed in the cold. The dry mixture was placed in an oven which had a temperature of 130 C. When the temperature of the mixture reached 80 C., the mixture began to melt. At 105 C. water started to volatilize. At 108C. the mixture had become completely transparent.

water. After warming slightly,

time all C. crystallization of the nonhydrolysis of the After maintainingthe temperature at 130 C. for five minutes, 9 grams (0.5 mol) of water had been driven oiT. k

15 grams ofthe material thus prepared were dissolved in 15 grams of water by heating at 75-il0 C. Upon cooling to 0 C. 15 grams of mannitol monoborate monocondensation product were obtained.

In its broadest aspect the invention resides in polycondensation product to the monocondensation product by H20 in any form, such as liquid watenwater vapor or any aqueous medium capable of in accordance with the equations set out above. In certain of the process claims, by a temperature at which water is eliminated by ebullition, I mean a temperature at which water is evolved by boiling. Thus, the initial reaction, by which the polycondensation products are formed, takes place at about 105 C. at atmospheric pressure with boiling, or at about C. at mm. pressure with boiling.

In the claims, by the term "boric acid I mean not only 'orthoboric acid, butalso metaboric acid, perboric acid and other boron acids which contain an OH group attached to the boron, such as tetraborlc acid ,and other polyboric acids. Similarly, by alkali metalborates, I refer, to the salts, not only of orthoboric acid, but also to the salts of perboric acid, metaboric acid, tetraboric acid, and all other boric acids referred to above. H This application is a continuation in part of my co-pending application Serial Number 149,839, filed June 23, 1937, disclosing and claiming Dulcitol and mannitol borates and salts thereof. In this application I claim the'method of preparing dulcitol and 'mannitol monoborate monocondensation products.

Having described my invention, what I claim is: 1. The process of preparing a water soluble derivative of a hexahydric alcohol selected from the group consisting'of mannitol and dulcitol, in which the hydrogen. atom of one secondary alco 1101 group has'been-replaced with the boron radis cal --B(OH)R, where Ri selected from the group consisting of 0H and metal; which comprises lhydrolyzing a borate polycondensation derivative oi the hexahydric alcohol by contacting said derivative with an aqueous medium capable of effecting hydrolysis and which does not destroy the hydrolysis prodefiecting hydrolysis 30 alkali metal salts of the M, M being an alkali not, said polycondensation derivative consisting of the hexahydric alcohol in which atom of a secondary alcohol group the hydrogen has been replaced by a boronradical selected from the group atom and replaces the hydrogen atom of a third.

alcohol group of said hexahydric alcohol.

2. The derivative the group consisting of mannitol and, dulcital, in which the hydrogen atom of one secondary alcohol group has radical -B(0H)R, where R is selected from the metal, which comprises hydrolyzing -a borate polycondensati n, derivative of the hexahydric alcohol by disso ving said derivative in an aqueous medium capable or effecting hydrolysis and which process of preparing a water soluble of a hexahydric alcohol selected from been replaced with the boron.

70 group consisting of 0H and 0M, M being an alkali does not destroy the hydrolysis product, said polycondensation derivative consisting of the hexahydric alcohol in which the hydrogen atom of a secondary al'coholgroup has been replaced by a boron radical selected from the group consistin of -BRR' and -BR'R, where R is selected from .the group consisting of 0H. and OM, M being an alkali metal, R is a bond to the oxygen atom and replaces the hydrogen atom oi a second secondary alcohol group of said hexahydric alcohol and R.

is a bond to the oxygen atom and replaces the hydrogen atom of a third alcohol group of said hexohydric alcohol.

3. The process of preparing a water soluble derivative of a hexahydric alcohol selected from the group consisting of mannitol and dulcitol, in which the hydrogen atom of one secondary alcohol group has been replaced with the boron radical -B(OH )R, where R is selected from the group consisting of OH and OM, M being an alkali metal, which comprises hydrolyzing a borate polycondensation derivative of the hexahydric alcohol by dissolving said derivative in an capable of effecting hydrolysis H- --OH on rho-o4; mon \R where R is selected from the group consisting of OH and 0M, M being an alkali metal, which com-- prises hydrolyzing mannitol monoborate dicondensation product of the following formula:

omen I no- H 3- -o \BR H- o where R. is selected from the group consisting of 0H and OM, M being an alkali metal, by dissolving the said dicondensation product in an aqueous 7 medium capable of effecting hydrolysis and which does not destroy the hydrolysis product.

5. The process 01' preparing mannitol monohorate, monocondensation product of the following formula:

. onion where R is selected from the group consisting of 0H and OM, M being an alkali metal, which comprises hydrolyzing mannitol diborate tetra- -condensation product of the following formula:

onion oo-n an 0 -n where R is selected from thegroup consisting of OH and OM, M being an alkali metal, by dissolving the said tetracondensation product in an aqueous medium capable of effecting hydrolysis and which does not destroy the hydrolysis product.

- 6. The process of preparing a crystalline water soluble monocondensation derivative ofa hexahydric alcohol selected from the group consisting of: -mannitol and dulcitol-in whichthe hydrogen atom of one secondary alcohol group has been replaced with the boron radical -B(OH)z, which comprises hydrolyzing a water soluble polycondensation derivative of said hexahydric' alcohol in which the hydrogen atom of a secondary alcohol group has been replaced with a boron radical selected from that group of radicals represented by B(OH)R', -BRR where R. is a bond to the oxygen atom and replaces the hydrogen atom or another secondary group of said hexahydric alcohol, and It is a bond to the oxygen atom and replaces the hydrogen'atom of a third alcohol group of said hexahydric alcohol by dissolving the said polycondensation derivative in water, and cooling the resulting solution to effect separation of saidmonocondensation derivative in crystalline form.

7. The process of preparing a crystalline water soluble monocondensation derivative of a hexahydric alcohol selected from the group consisting 4 dulcitol-in which the hydroofz-mannitol and gen atom of one secondary alcohol group has been replaced with the boron radical --B(0H)2, which comprises hydrolyzing a water soluble polycondensation derivative of said hexahydric alcohol in which the hydrogen atom 01 a secondary alcohol group has been replaced with a boron radical selected from that group of radicals represented by B(OH)R'; -BR'R", where R is a bond to the oxygen atom and replaces the hydrogen atom or another secondary alcohol group of said hexahydric alcohol, and RF is a bond to the oxygen atom and replaces the hydrogen atom of a third alcohol group of said hexahydric alcohol, by dissolving said polycondensation derivative in water at a temperature of approximately TO-80 0., cooling the resulting solution to a temperature of about 0 C. to efiect precipitation of said monocondensation'derivative in crystalline form, and separating the crystalline product so precipitated.

8, The process or preparing a crystalline water soluble monocondensation derivative of a hexahydric alcohol selected from the group consisting oiz-marmitol and dulcitol-in which the hydrogen atom of one secondary alcohol group has been replaced with the boron radical --B(OH) 2, which comprises hydrolyzing a water soluble polycondensation derivative of said hexahydric alcohol in which the hydrogen atom of a secondary alcohol'group has been replaced with the boron radical B(H)R', where R is a bond to the oxygen atom and replaces the hydrogen atom of another secondary alcohol group of said hexa- 9. The process of preparing crystalline man.-

nitol monoborate monocondensation product of the following formula:

which comprises hydrolyzing mannitol monoborate dicondensation product of the following formula:

onion j no- -n no- -u non HIOH

by dissolving the said dicondensation product in water, and coolingthe resulting solution to effect separation of said monocondensation product in crystalline form. v

10. The process of preparing crystalline mannitol inonoborate monocondensation product of the following formula: V A

which compriseshydrolyzing mannitol diborate tetracondensation product of the following formula:

' HOB -o HaOH by dissolving the said tetracondensation product in water, and cooling the resulting solution to efl'ect separation of said monocondensation prodnot in crystalline form.

11.'The process of preparing a water soluble monocondensation derivative of a hexahydric alcohol selected from the group consisting of:-

mannitol and dulcitol--in which the hydrogen borates to a temperature at which water is eliminated by ebullition for a suilicient period 0! time to form a water soluble polycondensation derivative of said hexahydric alcohol in which the hy-- drogen atom of a secondary alcohol group has been replaced with a boron radical selected from that group of radicals represented by -BRR,'; BR'R where R is selected from the group consisting of OH and OM, M being an alkali metal, R is a bond to the oxygen atom and replaces the hydrogen fatom of another secondary alcohol group of said hexahydric alcohoL'and R is a bond to the oxygen atom and replaces the hydrogen atom of a third alcohol group of said hexahydric alcohol, and hydrolyzing the polycondensation derivative thus formed to said monocondensation derivative by contacting the said polycondensation derivative with an aqueous medium capable of effecting hydrolysis and which does not destroy the hydrolysis product.

12. The process of preparing a water soluble monocondensation derivatives of a hexahydric alcohol selected from the group consisting of: mannitol and .dulcitol-in which the hydrogen atom of one secondary alcohol group has been replaced with the boron radical --B(OH) R, where R is selected from the group consisting of OH and 0M, M being an alkali metal, which comprises heating a mixture of the hexahydric alcohol and a boron compound selected from the group consisting of borlc acid and alkali metal borates to a temperature at which water iseliminated by ebullition for a sufliclent period of time to form a water soluble polycondensation derivative of said hexahydric alcohol in which the hydrogen atom of a secondary alcohol group has been replaced with a boron radical selected from that group of radicals represented by --BRR'; -lBRR where R is selected from the group consisting of 0H and OM, M being an alkali metal. R!

is a bond to the oxygen atom and replaces I the hydrogen atom of another secondary alcohol group of said hexahydric alcohol, and R is a bond to the oiwgen atom and replaces the hydrogen atom of a third alcohol group oi said hexahydric alcohol and hydrolyzing the poly-- condensation derivative thus formed to said, monocondensation derivative by dissolving the said polycondensation derivative in an aqueous medium capable of effecting hydrolysis and which does not destroy the hydrolysis product.

a 13. The process of preparing a water soluble monocondensation derivative of a hexahydric alochol selected from the group consisting oi:' mannitol and duicitol-in which the hydrogen atom of one secondary alcohol group has been replaced with the boron radical -B(QH) R, where R is selected from the group consisting of OH and OM, M being an alkali metal, which comprises heating a mixture of the hexa-hydric alcohol and a boron compound selected irom the group consisting of boric acid and alkali metal borates to a temperature at which water is eliminated by ebuliition for a sufficient period 01 time to form a water soluble polycondensation derivative of said hexahydric alcohol in which the hydrogen atom of a secondary alcohol group has been replaced with the-boron radical --BRR',

where R is selectedfrom the group consisting of drogen atom of another secondary alcohol group or said hexahydric alcohol, and hydrolyzing the polycondensation derivative thus formed to said [I monocondensatlon derivative by dissolving the said polycondensation derivative in an aqueous 'borate monocondensation product of the followmediumcapable of efiecting'hydrolysis and which does not-destroy the hydrolysis product. 14. The process of preparing mannitol monoing formula:

CHzOH no=- '-H n- -on on n-e-o-m where R. is selected from the group consisting of 0H and OM, M being an alkali metal, which comprises heating a. mixture comprising mannitol and a boron compound selected from the group conv sisting of boric acid and alkali metal borates in the proportion of one mol of mannitol to one mol of boron present in the. reacting miture, to a temperature at; which water is eliminated by ebulll tion for a sumcient period of time to form mannitol monoborate dicondensation product of the following formula:

' CH:0H'

where R is selected from the group consisting of OH and OM, M being an alkali metal, and hydrolyzing the dicondensation product thus'formed to said monoccndensation product by dissolving the said dicondensation product in an aqueous medium capable of effecting hydrolysis and which does not destroy the hydrolysis product.

'15. Theprocess of preparing mannitol monoborate monocondensation product of the follow-v ing formula:

' onion no- -n,

no- --a n- OB where R is selected from the group consisting of 0H and OM, M being an alkali metal, which comprises heating a mixture comprising mannitol and a boron compound selected from the group cons'isting of boric acid and alkali metal borates, in

the proportion of one mol of mannitol to two mols of boron present in the reacting mixture, to a temperature at which water is eliminated by ebullition for a 'sufflcient period of time to form.

mannitol diborate tetracondensation product of the following formula:

- CHHOH where a is selected from the group'consisting of 

